The acoustical characteristics of stringed instruments, such as guitars, and in particular, classical guitars which are not electronically augmented, are affected by the length of the strings producing the sound vibrations. Accurate tuning of the string cannot solely be regulated by adjusting the string tension, and the points of support of the string are also critical and significantly affect the pitch produced.
String vibrations are transmitted to the guitar front panel through a bridge affixed to the front panel, and bridge arrangements are known whereby the point of location of string support at the bridge may be adjusted to lengthen or shorten the string unsupported length. For instance, adjustable string supporting bridges are shown in U.S. Pat. Nos. 490,528; 688,272; 934,678; 1,138,803; 2,491,788; 3,178,985 and 4,208,941. While the string rests shown in the prior art, such as the aforementioned patents, permit adjustment of the effective string length, the bridges are of a custom construction to support the particular rests disclosed, and the inventive concepts shown in these patents cannot readily be applied to existing guitars with standard bridge systems.
It is an object of the invention to provide a guitar bridge system utilizing a plurality of individual string rests wherein the rests are compatible with standard guitar bridges and no modification to the bridge is required to use the string rests of the invention.
A further object of the invention is to provide a rest for stringed instruments wherein the rest is compatible with standard guitar bridge configurations, and the rests permit the string to be supported at selective heights from the guitar front panel and fingerboard or neck.
Another object of the invention is to provide a rest for a stringed instrument of a simple form wherein the rest is compatible with standard bridge configurations and is capable of lengthening or shortening the effective string length, as well as determining the height of the string.
A further object of the invention is to provide a string rest for guitars wherein the rest is located adjacent the neck nut and is capable of supporting a string at a predetermined height above the fingerboard, and simultaneously shorten the effective string length.
An additional object of the invention is to provide an internal bracing system for guitars interposed between the front and rear panels to improve the acoustical and structural characteristics, such bracing capable of being installed after the guitar is assembled.
In the practice of the invention a standard classical guitar includes a bridge affixed to the front panel having an elongated slot defined therein. The bridge includes anchor means for holding the ends of the string, and rests are defined upon the bridge over which the strings pass and are supported. In accord with the invention the string rests include a lower base region firmly received within the bridge slot for selective positioning therein, and the rests include an upper portion which engages and supports the strings passing thereover. The upper edge of the rests is obliquely oriented to the length of the slot and notches are defined in the rests' upper edge for receiving and holding the string in the desired position.
Further, the string rests' upper portion may also be offset with respect to the base region wherein the location of string support at the rest upper edge is offset "forwardly" or "rearwardly" with respect to the rest base region. This offset will increase or shorten the effective string length depending on whether the rest offset portion extends in the direction of the neck, or away therefrom.
In accord with the invention the string length may also be shortened by the use of a string rest supported upon the string neck adjacent the nut located at the outer end of the neck. This string rest includes a flat bottom surface for engaging the guitar neck, and the upper surface is obliquely oriented to the bottom surface having string receiving notches defined therein wherein a string supported by a notch will be maintained above the neck at the height determined by the associated notch. This rest may be moved along the neck toward and away from the bridge, and thereby effectively vary the length of the vibrating portion of the string, and also, this rest will adjust the height of the string above the neck adjacent the nut.
The tonal character of a guitar is affected by the vibration characteristics of the front and rear panels, and such characteristics can often be improved in an acoustical guitar by the imposition of reinforcing or bracing structure intermediate the front and rear panels. In accord with the invention a prop of elongated form having shaped ends is interposed between reinforcing ribs supporting the front and rear panels, and the length of the prop may be varied by screw means to adjust the degree of compression within the prop.
The aforementioned apparatus permits guitars and similar stringed instruments to be more finely tuned than is possible with merely varying the string tension, and as the string rests and prop are readily usable with standard guitar constructions no modification to the guitar is required to employ the inventive principles.